Conserve Wildlife Blog

Posts Tagged ‘beach nesting birds’

Birds in better condition than last year but still face an ecological roulette

Wednesday, July 11th, 2018

by Larry Niles (Part 3 of 3)

With the stopover period winding down, we can say the red knot and other shorebird species left the bay in better condition than the disastrous condition of last year. So what does it mean?

First, the last four years have been a sort of ecological roulette for the birds. Horseshoe crab numbers remained at only 1/3 the potential population possible on Delaware Bay leaving birds at the mercy of good conditions to get enough eggs. Last year, water temperatures stayed low during the mid-May depressing the spawn and the density of eggs. Although the average was 8000-eggs/square meter, there were less than 2000 eggs/ meters square in the month of May.

This year, the weather and water temperature added to a good spawn in May and the birds appeared to have left in good condition. Unfortunately, it’s only chance. If bad weather or cool temperatures return, they will face another bad year. We need more crabs to smooth out the rough years. The bay can support three times the current number.

An increase in the number of horseshoe crabs would transform the bay. In 1990 and 1991, we had three times the number of crabs we have now. But we had 10 times the density of eggs because of multiple breedings by females and more eggs reaching the surface as one crab digs up another’s eggs. Additionally, it lasted for two months, unlike this year’s eggs, which lasted only a few weeks.

Dr. Larry Niles has led efforts to protect red knots and horseshoe crabs for over 30 years. Read the paper that describes the work of a team of scientists measuring egg densities in 1991 before the overharvest of crabs here.

Red Knot over 180g ready to leave the bay for the Arctic breeding grounds. Photo by Stephanie Feigin.

Good horseshoe crab egg densities draw 34,500 Red Knots to the bay

Monday, July 9th, 2018

by Larry Niles (Part 2 of 3)

The best news is a direct consequence of these good conditions, the number of knots and turnstones increased this year. Our season-high estimates show that there are 34,500 knots in the bay and 21,000 ruddy turnstones. These may be the highest counts on the bay in at least 15 years.

Why? At first one would conclude the increased numbers on the bay represent a real increase in the size of the population, but it is not. Shorebirds need time to respond to improving conditions because they are relatively slow breeders, as are most Arctic breeders. Knot numbers on Delaware Bay basically depend on the availability of crab eggs. In bad years, numbers go down because birds come to the bay and leave quickly.

This was the case last year. Egg densities during May plummeted to less than a few thousand-eggs/meter2.  Knots banded in Delaware Bay were resighted days after release in other stopovers like Cape Cod. Consequently, our Red Knot count on the bay fell from 24,500 in 2016 to 17,500 in 2018. We assumed this was not a real decrease in numbers, but the result of birds leaving right after finding eggs too scarce or competition too intense on the bay.

This year we found good egg densities, and birds staying long enough to be counted. The aerial and ground counts detect only a portion of that number depending on the total number of red knots and the egg density. The longer birds stay, the greater the proportions of the total are seen on one day. So this year we had good egg densities, good weights, and good numbers. It was one of the best of seasons in recent memory.

Dr. Larry Niles has led efforts to protect red knots and horseshoe crabs for over 30 years.

A red knot flock near Straight Creek on Egg Island in NJ. This flock was one of several on Egg island that totaled over 13,000, a third of the entire bay flock. The birds use this remote marsh as a staging site before flying off to the Arctic.

Shorebirds on Cooks Creek Inlet seen from Cooks Beach. The birds practically reside in this inlet and the four others that flow from the marsh behind the beaches from Reeds Beach to Pierce’s Point.

Horseshoe crabs expanded breeding into neap tides

Saturday, July 7th, 2018

by Larry Niles (Part 1 of 3)

The horseshoe crabs extended their breeding period into the neap tide phase after the cold weather of mid-May decreased water temperature during the spring tides.  The crabs roughly require a water temperature of about 59 degrees F before breeding begins in earnest.  Crabs still breed at a lower temperature, but many more will breed above the temperature threshold.

At the same time, crabs also look for spring tides, the higher high tides that come with full and new moons, because they can breed in sandy places unavailable at lower tides. This year the water cooled during the new moon spring tide and warmed in the neap.  Good spawning during the neap tides of the last week was welcome good news.  This May good spawning conditions will raise average egg densities about 50% higher than last year.

We found eggs lying on the beach in many beaches including Reeds Beach at the Jetty.  This is better news then it first appears.  Last year shorebirds desperately fed on the eggs at the jetty and beach corner at North Reeds to the delight of many visitors.  Little did they know, the birds couldn’t find eggs elsewhere at similar densities and would have avoided the place if they could. The good news this year is they have.

Higher egg densities on the New Jersey’s Delaware Bayshore gave shorebirds a welcome boost.  Most gained weight rapidly.  The weights of red knots and ruddy turnstones show the difference.  Knots rapidly reached the 180-gram threshold considered necessary for birds to reach the Arctic breeding areas in good conditions, and Ruddy Turnstones are in similarly good condition.

Dr. Larry Niles has led efforts to protect red knots and horseshoe crabs for over 30 years.

A view from the Reeds Jetty looking south. Horseshoe crab eggs piled up after a few days of southerly winds but unlike last year shorebirds did not pile into eat them. It a good sign. The jetty exposes the birds to intense disturbance and they would rather feed in more secure places – and they did because they could.

Horseshoe Crab breed on the sod bank of Egg Island and shorebird feed on the eggs as they are being laid. The breeding attempts must fail because eggs cannot incubate in the anoxic environment of marsh mud but its a good sign the crabs are breeding in odd places.

CWF Scientists Follow At-Risk Migratory Shorebirds to Tierra del Fuego

Wednesday, February 7th, 2018

by Stephanie Feigin, Wildlife Ecologist

 

Over the past two years, our team, with the help of funding from the Neotropical Migratory Bird Conservation Act, has worked to create critical habitat maps and detailed threat maps for at-risk shorebird species in Northern Brazil and in Tierra Del Fuego, Chile. These projects have established the foundation for conservation planning in these important wintering areas for migratory shorebirds like red knots.

 

Brazil:

Two years ago, our team began working in Northern, Brazil covering the Atlantic coastline of both Pará and Maranhão state between Belém and São Luís. Our team conducted two successful excursions to Brazil taking point count surveys of wading shorebirds collecting approximately 44,700 individual bird sightings to add to the database our team created for the critical habitat maps (Figures 1 & 2).

Figure 2. Results from the 2017 point count survey

                    Figure 1. Results from the 2016 point count survey

 

David Santos and Larry Niles conduct point sampling surveys in Maranhão Brazil.

We conducted surveys using point count methods using fixed radius plots positioned along transects, with all wading birds counted within the 250m radius. Transects were conducted by either walking or while in a boat across various tidal stages and a variety of habitat types including mangrove creeks, sand flats, mudflats and beaches.

 

 

 

Brazil Team: Carla Meneguin,
Paulo Siqueira, Ana Paula Sousa, Larry Niles, Juliana Almeida, Carmem Fedrizzi Joe Smith, Stephanie Feigin, Yann Rochepault, Laura Reis and Christophe Buiden (photo by Juliana Almeida)

 

 

 

Our team then created threat maps of the region from coastal development, mining operations, offshore drilling, and shrimp farming to help inform future conservation planning and mitigate impacts of these activities to the critical shorebird habitat in the region.

 

Chile:

This year, with a second round of funding, our team conducted work in Tierra Del Fuego, Chile to create critical habitat and detailed threat maps for Bahia Lomas in Chile. Bahia Lomas is both a globally significant RAMSAR wetlands site and a Western Hemisphere shorebird site of hemispheric importance.  

 

Shorebirds in Bahia Lomas

Historically, Bahía Lomas and nearby Rio Grande supported wintering populations of 67,000 red knots –  the largest wintering area for knots in the Western Hemisphere. In the last 30 years, however, the population has declined to less than 15,000 knots in Bahía Lomas and the population in Rio Grande is functionally extinct (Morrison et al 1989).

 

 

Aerial Survey over Bahia Lomas

 

 

 

This January our team conducted surveys along the coast of Bahia Lomas to understand distribution of shorebird species within the region, using the same sampling methods, study key roosting and feeding habitats, and delineate critical habitat and threats to the region to inform future conservation and minimize impacts to shorebird populations.

 

Team in Chile including Ross Wood, Stu Mackenzie, Carmen Espoz, Larry Niles, Joe Smith, Yann Rochepault, Christophe Buidin, Antonio Larrea, Richard Lathrop, Stephanie Feigin and Amanda Dey.

Over two weeks our team of New Jerseyans and Canadians conducted point-count sampling surveys throughout the bay with large assistance from our partners from Universidad Santo Tomás in Chile to determine key habitats. Additionally, our team conducted four aerial surveys to get species distribution counts on a large scale of the whole bay at various tide stages, as well as a helicopter survey to continue the population counts of the region done by Dr. Guy Morrison. Finally, our partners with the Universidad Santo Tomás conducted marine invertebrate sampling surveys. These data will be combined to aid in the creation of a GIS mapping system that can identify the most important shorebird habitats in the region.

 

 

 

 

 

In the next few months our team will use these data and overlay them with threat mapping to determine the critical habitats undergoing the greatest threats.  This project is designed set the stage for proactive conservation planning that will mitigate future threats and will hopefully uncover the source of ongoing declines to the shorebirds in this region.

Citation:

 

Morrison R.I.G. & Ross R.K. (1989) Atlas of Nearctic shorebirds on the coast of South America. Canadian Wildlife Service Ottawa (Canada).

 

2017: Piping Plover Nesting Season

Thursday, November 16th, 2017
How did they do?

Emily Heiser, CWFNJ Wildlife Biologist

Statewide pair-nest success was down this year, but remains above the long-term average. photo by Northside Jim.

For the 12th year in a row, the Conserve Wildlife Foundation of New Jersey, in partnership with New Jersey Division of Fish & Wildlife’s Endangered and Nongame Species, assisted in monitoring and managing the state’s Beach Nesting Bird Project.  Four species are regularly monitored throughout the field season: piping plovers (federally threatened, state endangered), least terns (state endangered), black skimmers (state endangered), and American oystercatchers (state species of special concern). Statewide, piping plovers are of particular concern as their numbers continue to decline and federal recovery goals have not been achieved.  (more…)

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